We examine the H i-to-stellar mass ratio (H i fraction) for galaxies near filament backbones within the nearby Universe (d < 181 Mpc). This work uses the 6-degree Field Galaxy Survey and the Discrete Persistent Structures Extractor to define the filamentary structure of the local cosmic web. H i spectral stacking of H i Parkes all sky survey observations yields the H i fraction for filament galaxies and a field control sample. The H i fraction is measured for different stellar masses and fifth nearest neighbour projected densities (Σ5) to disentangle what influences cold gas in galaxies. For galaxies with stellar masses log(M⋆) ≤ 11 M⊙ in projected densities 0 ≤ Σ5 < 3 galaxies Mpc−2, all H i fractions of galaxies near filaments are statistically indistinguishable from the control sample. Galaxies with stellar masses log(M⋆) ≥ 11 M⊙ have a systematically higher H i fraction near filaments than the control sample. The greatest difference is 0.75 dex, which is 5.5σ difference at mean projected densities of 1.45 galaxies Mpc−2. We suggest that this is evidence for massive galaxies accreting cold gas from the intrafilament medium that can replenish some H i gas. This supports cold mode accretion where filament galaxies with a large gravitational potential can draw gas from the large-scale structure.
Bibliographical noteThis article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, 466(4), pp.4692–4710. The original publication is available at https://doi.org/10.1093/mnras/stw3328. Copyright 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
- galaxies: evolution
- galaxies: general
- large-scale structure of Universe
- radio lines: galaxies